Hello!

I am buying a bike for my Dad, and the only thing I know is that he's 5'7" with an 80 cm standover.
should i get a 50 cm? 52 cm?

He'll be visiting in Feb. and wants to go on a ride with me. I do have two bikes, one of them is 42cm but the other is 47cm with a 76cm standover.

Do you think my Dad can just make do with my spare bike? One thing I know is that he doesn't like aggressive riding positions, so on my 47cm the handlebar might be a bit low.

Any suggestions?